Electronic crash sensors are commonly employed on vehicles to sense vehicle dynamics. In particular, satellite crash sensors are used for vehicle crash detection systems to sense frontal and side impact during a vehicle crash (collision). To effectively detect vehicle crashes, many vehicle crash detection systems require satellite crash sensors mounted in crush zones of the vehicle. The signal outputs of satellite crash sensors located in select crash zones typically offer optimal signal-to-noise ratio.
Many vehicle crash detection systems require several satellite crash sensors at selected locations to ensure accurate detection of a vehicle crash. For example, air bag deployment systems typically employ a multitude of sensors for sensing longitudinal and/or lateral acceleration (or deceleration). Currently, vehicles are typically equipped with pressure sensors and acceleration sensors (accelerometers). Pressure sensors are generally located in the vehicle door crush zone. Accelerometers are commonly located in a rigid beam, such as the vehicle A-pillar.
In conventional packaged sensor modules, pressure sensors and/or accelerometers are typically packaged individually. One example of a conventional satellite crash sensor module employed on a vehicle is illustrated in FIG. 1. The conventional sensor module 100 shown includes a plastic overmolded housing 112 and a printed circuit board 140 made from an alumina hybrid substrate. The circuit board substrate 140 is generally located in a recessed chamber 114 in housing 112, which is typically covered. The housing 112 is bolted to a vehicle via bolts extending through two mounting holes 116 and 117, and the connector end 118 is plugged into an electrical interface connector. The sensor 124 and related sensor signal processing electronics 144 are generally located on the alumina hybrid substrate 140 or FR4 printed circuit board.
The placement of the sensor on an alumina-based substrate allows for a cost affordable sensor module, however, a number of drawbacks exist. The alumina-based substrate is relatively large as compared to the circuitry used in a typical satellite crash sensor. Additionally, there is generally little flexibility and insufficient room to add a second sensing technology within a common housing. Also, the electromagnetic interference (EMI) requirements of an alumina-based sensor are generally difficult to meet due to the large area and lack of adequate shielding. The housing generally must be sufficiently rigid to ensure that the crash signals are accurately transmitted to the sensor on the substrate. Further, the large area of the alumina-based substrate generally requires multiple mounting bolts to ensure a high resonant frequency to avoid distortion of input signals generated during a crash.
It is therefore desirable to provide for a compact and cost affordable sensor module. In particular, it is desirable to provide for a sensor module that may be conveniently employed as a crash sensor on a vehicle. It is further desirable to provide for such a crash sensor that is relatively immune to electromagnetic interference and can be easily mounted onto the vehicle.